the flyin' scotsman

First I should thank Colin (Lizard 931) for the council and Roger (928sRus) for the parts

My S4 brakes have been slightly upgarded. The rears are cast in hole rotors, stock calipers and PBR ceramic pads. The fronts are cast in hole rotors, stock calipers (fully checked but not rebuilt and painted RED) with PBR ceramic pads. The master cylinder is stock, the bias valve is changed to the 33 bar and the fluid is fresh ATE Super Blue. Brake lines are Goodrich steel braided.

The brakes pads when new are a tight fit in the caliper guides so to avoid squeeling you clean the guides, trim and champher the pads and apply anti-seize to the brake pad plate.

I cleaned the caliper guides with a toothbrush style wire brush and left them in place in the calipers. I also used brake cleaner and got the guides very clean.

The brake pads can be trimmed with a file but I chose to use my bench grinder. I trimmed metal from the backing plate on the edges that ride on the caliper guides.........not a lot but enough to have the pads easily slide in and out the caliper. I rounded the bottom corner also. Now with a file I champhered the leading edge of the pads.

Final step was to 'coat' the pad backing with anti-seize where the edges were trimmed and where the caliper pistons engage the pads. The OEM noise dampers were omitted.

Pads installed and wheels refitted/torqued the next task is to bed in the pads. Running the car on an empty highway I braked moderately from 100 to 10 kph accellerate back to 100 and repeat. I did his 9 times which got the brakes quite toasty. Colin recommends then flushing/bleeding the brakes...........I didn't as I had good fresh fluid in the system.

Brakes are now very strong and silent

dr bob

Malcolm--

Rotors refaced for the new pads? And how's the stopping?

Thanks for all the tips on installation too.

I have Metal Masters in there now but will be replacing them in the next year. I like the relatively low dust from the MM's, but they do have just a hint of noise sometimes at the end of low-speed stops.

the flyin' scotsman

thx Dr. Bob.

Rear rotors were new last year with new pads............front rotors are new this year again with new pads.

Braking is very strong and little/no dust.........extremely happy with the outcome

Lizard928

One thing to note is that when I do the bedding proccess. 100-10-100-10,,,,,,, I do not brake or accelerate moderately. I do this to the limit of the car, threshold braking, and maximum acceleration.

The never-sieze used can be either lowtemp (silver colour), or high temp (copper colour), either one will work well. And continue to work even in track duty.

Glad I was able to help you achieve a squeek free ride Malcolm.

the flyin' scotsman

I used the word moderately as it was still quite cool .............~+3C, didn't want to slide off the island.

Its much warmer today; perhaps I'll go again.

Lizard928

If they are silent then they are at least partially bedded. I would wait, and if they start to make any noise in the future repeat the bedding procedure at that time.

odurandina

thanks Colin, Malcom, hey Colin, who is the russian beauty ? or are we talking Ukraine.


i've got stick solid rotors...

what i am really confused about is why what is behind the pad is so crucial... not that i don't barely understand the discussion in the first place.

Lizard928

The difference is that neversieze is a lubricant. It gets a layer between the two metal surfaces, like the pad backing plate and caliper pistons.
This allows slight variances and changes to move easily instead of squeeling.

Randy V

It's always a trade-off between low dust and low noise.

That said, I'm real happy with the last set of front pads I got from 928 Specialists.

Basically zero dust and very quiet.

Damned if I can remember which brand they are though!

GregBBRD

I was following this and the other thread about the blue Pagids...wondering what the magical secret to making Pagids not squeak, on the street.

Now I know how to do this...use PBR's.

Seriously, it is really tough to make a PBR squeak....you have to work at it. Any of the Pagid performance pads are pretty much just the opposite...tough to keep quiet.

White Lightnin'

If they are the same ones recommended to me by 928Sp... they are Mintex. Very little dust or noise (at least when they were new). Now, I only get a squeal at low speeds and light braking... they are silent when aggressively braking.

Still, I am going to be adding 'silencer' inserts at all 4 corners in the near future... the squeal unnerves some passengers.

NoVector

Colin - Will popping out existing pads and putting anti-sieze on them do anything to stop the squeal? Or is this something to do when installing new? The noise on my GTS front brakes is terrible... I've thought about installing new rotors and pads but would like to kick that can down the road if I can.

Thanks! / Bruce

odurandina

before having them installed, i baked the calipers in the oven at 350 degrees for about 30 minutes and then sprayed regular yellow paint on - (i was too lazy to use high-heat, caliper paint as i figured it would not be necessary) - and then the gloss - with the blazing hot calipers suspened from a wire.

the yellow coating is very hard, and you can spray the brakes with the powerwasher without any paint flaking off.




.

JHowell37

FWIW, the high pitched squealing sound that brakes sometimes make comes from the area where the caliper piston contacts the back of the pad. That's why they sell those shims that snap onto the back of the pads or snap into the pistons (like Brembo calipers.) That's why that aerosol stuff appropriately labeled "disc brake quiet" is sprayed on the back of the pads. These things all serve as a buffer between the back of the pad and the caliper piston. The noise is produced as a result of vibration between the pad and the piston. The spray and shim are a damper.

While there are certainly some other benefits to replacing the rotors, good rotors or **** rotors have little bearing on the noise.

One final thing, one characteristic of ceramic brakes is their lack of noise. PBR ceramic pads are not an exception.

Lizard928

If you do this, also shave the sides down. Part of the noise is from the pistons rubbing on the back, part of it is pad being too tight in the caliper due to dust build up under the stainless guides, and part of it is the pad composition on metal.
The last is why a proper bedding procedure is required. When properly bed some pad material is actually bonded to the surface of the rotor and you are then braking with pad material to pad material, this is actually the biggest affect on the noise. But the other items are needed.

I do however agree with GB that the PBR pads are excellent pads, and for a street car with minimal track time they are the way to go! But without proper prep they too will squeel. If you are doing lots of track time, get a set of track pads to swap over when you go to the track.